During Winter, I sometimes set up a grille-block, but I'm hesitant this Summer. The transmission has a cooler line that runs into an isolated corner of the rad. Today, I ended up thinking about airflow over that section and the implications of blocked flow.

With the kickdown cable tightened to activate the TC asap, heat is a consideration.

Has anyone monitored tranny temps with grille blocks on automatics? Once I get a few hours in the garage, I'm thinking of replacing the fluid with Synthetic (if that helps). Should a transmission temp gauge be installed as well?

Synthetic fluid will help for sure, That is where the synthetic shines, extreme hot or cold. Synthetic tranny fluid will take a lot more heat than dino. Also some claims are made that synthetic oil runs cooler.
I would think having a little air flow over that isolated corner would be helpful.
I say if in doubt open up the grill a little, you wont loose that much FE.

ford offered a external trans filter with your new rebuilt trans, it was just a external in line filter with some fins on it to help a bit more with cooling the fluid. i'm pretty sure you could use it on any trans with the rubber cooler lines.

A change to synthetic would definitely help, and opening your grill block a little so that the flow goes over the transmission cooler would be beneficial as well. Have you considered installing a small electric fan on your transmission cooler? Maybe that would help too, maybe a PC case fan?

A change to synthetic would definitely help, and opening your grill block a little so that the flow goes over the transmission cooler would be beneficial as well. Have you considered installing a small electric fan on your transmission cooler? Maybe that would help too, maybe a PC case fan?

I have a box full of PC fans -- great idea! That would draw very little current as well.

I don't think pc fans will blow enough air to influence a/t fluid temperatures to any significant degree. I think a car moving even 5-10 mph will have faster airflow over the fins as long as the air path is open.

I wouldn't try to create airflow with a fan when there's essentially free airflow from the car's movement. My two cents.

However, I could certainly see using the PC case fan to exhaust hot air from the engine bay through the...wheel wells, for instance.

rh77 - towards the idea of keeping the tranny cool?? If you're worried, put in a gauge. It's not going to hurt anything, and may help tell when the tranny gets warmed up in the wintertime.

You could also go with an aftermarket tranny cooler. Take the fluid out of that portion of the rad, as it serves to heat the engine coolant while it cools the tranny fluid. They're easy to install, and not too outrageously expensive....

On the trannie cooler: Unless it's thermostatically controlled, I believe you need to install that BEFORE the radiator (I'm dredging stuff up from the hot-rod days here) . The trannie needs to run in a certain temperature range, so running the fluid through the radiator not only cools it, but guarantees it returns to the trans at a decent temp (180-200?). A thermostic cooler will also ensure the trannie fluid is not over cooled.

rh77 - Speaking of trannie coolers, I've got one you can have for free. Just let me know if you're interested.